Question

Define the mean chart

Answer 1

The mean chart `(bar"X"  "chart")` is used to show, the quality average of the samples taken from the given process.

The `bar"X"` charts are usually required for decision making to accept or reject the process.

Procedure for `bar"X"`

i. Let X₁, X₂, X₃, etc. be the samples selected each containing “n” observations usually (n = 4.5 or 6)

ii. Calculate mean for each samples `bar"X"_1,  bar"X"_2,  bar"X"_3`, ......... by using `bar"X"_"i" = (sum"X"_"i")/"n"`, i = 1, 2, 3, 4, ….

Where `sum"X"_"i"` = Total f “n” values included in the sample X₁.

iii. Find the mean `(bar"X")` of the sample means 

`bar"X" = (sumbar"X")/"Number of samples"`

Where `sumbar"X"` = Total of all the sample means.